Abstract: The FMR line shape modeling of non-interacting magnetic nanoparticles system was studied.As an example:the ferromagnetic has obtained the free energy F from the system in the presence of an applied field,the relation between resonance field Hr and effective anisotropy field HAeff was educed.The results is in consonace with the research conclusion of Raikher and Stepanou etc.It has been analyzed the linewidth of resonance field and compared with the results of Smit and Beljers,and come to the conclusion that the effective anisotropy field HAeff in the superparamagnetic regime is considered as a perturbation to the Zeeman interaction and added to the applied field H.Especially,while the difference between these approaches is negligible for small HAeff(high temperature regime),it becomes more pronounced when HAeff≈H.This article show how these results influence the determination of the parameters characterizing an array of random particles.